Oxygen breathing controls are normally used to supply oxygen to users at high altitudes. Common users are parachutists and airborne military personnel in an unpressurized aircraft. A user aboard an unpressurized aircraft has the use of an oxygen supply tank, i.e., aircraft-mounted prebreather. A pre-breather system supplies 100% oxygen to the user which serves to denitrify the user's blood. Utilization of the aircraft-mounted system also conserves parachutist's personal oxygen supply for a later use during a parachute descent. Before exiting the aircraft, the parachutist switches from an aircraft-mounted prebreather to his/her personal oxygen supply.
A cabin crew member user who must perform duties during a flight may use a portable oxygen system for mobility within the aircraft cabin or may access to an aircraft-mounted prebreather to conserve oxygen in the personal supply.
Conventional control systems have many areas that need improvements. An existing unit is CRU-79/P which is a chest mounted, 100% oxygen, positive pressure regulator. A majority of conventional regulators use a spring-loaded diaphragm/poppet/guide/seat arrangement. Such a mechanical design has inherent problems with a leakage when closed which is caused by a poorly seated poppet. For example, the conventional diaphragm often has an asymmetric contact with a related body seal and imprecise guide into which a diaphragm stem could move. Further, the spring loading the conventional diaphragm weakens.
Prior art breathing regulators have a problem in that approximately 10% volume is lost to the atmosphere. A conventional breathing regulator continuously bleeds oxygen to atmosphere even when it is not in use. The bleeding loss continues as long as the breathing regulator is connected to an oxygen source. The bleed rate can be approximately 0.75 lpm. Under normal breathing conditions, a breather consumes approximately 8 lpm. Thus, a 0.75lpm bleed rate represents approximately a 10% volume loss to atmosphere. For a parachutist who must descent from a high altitude with a personal oxygen cylinder of relative low volume, a loss of 10% oxygen volume could have a significant effect.
Therefore, it is an object of the present invention to provide an oxygen breathing control which facilitates its manufacturing, stocking, assembly and testing processes. One of the objects of the present invention is to provide an oxygen breathing control having a valving module containing no mechanical moving parts. Another object of the present invention is to provide a pneumatic valving module. Yet another object of the present invention is to provide an oxygen breathing control having a valving module which does not leak when fully closed. Another object of the present invention is to provide a valving module which is sensitive to breathing pressure changes and has a valve liner with a long service life. It is one of the objects of the present invention to provide an oxygen breathing control which is oxygen efficient. It is also an object of the present invention to provide an aneroid which controls breathing pressure schedule at a higher altitude of 34,000 to 45,000 feet.
Other improvements and benefits and usefulness of the present invention will become apparent as a reader proceeds through the explanations below.